In general, the mirror polishing of a semiconductor wafer such as a silicon wafer, a lens, a glass substrate, or some other is divided to rough polishing for a main purpose of adjusting the polished matter in flatness and in-plane evenness, and finish polishing for a main purpose of improving the matter in surface roughness, and removing scratches.
The finish polishing is usually attained by causing sueded artificial leather made of a soft foamed polyurethane to adhere onto a rotatable table, and rubbing a wafer against the leather while a polishing agent wherein colloidal silica is contained in an aqueous
s alkali-based solution is supplied thereonto (Patent Document 1).
However, when the polishing layer, which is made of the foamed polyurethane used for finish polishing, is low in flatness, there is caused a problem that tiny undulations are generated in the surface of the matter to be polished. The tiny undulations have been in particular considered to be a problem in the field of recent finish polishing. Thus, it has been intensely required in the market to supply a polishing pad capable of attaining a further decrease of tiny undulations.
Patent Document 2 listed up below describes a polishing cloth, for decreasing tiny undulations generated in the surface of a matter to be polished, wherein a polyurethane foam is arranged for a surface layer. However, this document never describes any specific formulation or composition of the polyurethane foam, or any matter related thereto. Furthermore, the cloth has a room for a further improvement from the viewpoint of the effect of decreasing the tiny undulations.    Patent Document 1: JP-A-2003-37089    Patent Document 2: JP-A-2004-136432